According to Treasury website:

PSP2 APPLICATION DEADLINES

To receive responses on their applications as quickly as possible, applicants should submit their web-based application form not later than 11:59 p.m. EDT on January 14, 2021. Applications received after 11:59 p.m. EDT on January 14, 2021 will be considered, but may not be processed as quickly. Applications received after 11:59 p.m. EDT on January 25, 2021, may not be considered, although Treasury may, at its discretion and subject to the availability of funds, consider such applications.

From the Omnibus bill passed by Congress:
SEC. 404. REQUIRED ASSURANCES. (a) IN GENERAL.—To be eligible for financial assistance under this subtitle, a passenger air carrier or a contractor shall enter into an agreement with the Secretary, or otherwise certify in such form and manner as the Secretary shall prescribe, that the passenger air carrier or contractor shall— (1) refrain from conducting involuntary furloughs or reducing pay rates and benefits until— (A) with respect to passenger air carriers, March 31, 2021; or (B) with respect to contractors, March 31, 2021, or the date on which the contractor expends such financial assistance, whichever is later; (2) ensure that neither the passenger air carrier or contractor nor any affiliate of the passenger air carrier or contractor may, in any transaction, purchase an equity security of the passenger air carrier or contractor or the parent company of the passenger air carrier or contractor that is listed on a national securities exchange through— (A) with respect to passenger air carriers, March 31, 2022; or (B) with respect to contractors, March 31, 2022, or the date on which the contractor expends such financial assistance, whichever is later; (3) ensure that the passenger air carrier or contractor shall not pay dividends, or make other capital distributions, with respect to common stock (or equivalent interest) of the air carrier or contractor through— (A) with respect to passenger air carriers, March 31, 2022; or (B) with respect to contractors, March 31, 2022, or the date on which the contractor expends such financial assistance, whichever is later; and (4) meet the requirements of sections 405 and 406. (b) RECALLS OF EMPLOYEES.—An agreement or certification under this section shall require a passenger air carrier or contractor to perform the following actions: (1) In the case of a passenger air carrier or contractor that received financial assistance under title IV of the CARES Act— (A) recall (as defined in section 401), not later than 72 hours after executing such agreement or certification, any employees involuntarily furloughed by such passenger air carrier or contractor between October 1, 2020, and the date such passenger air carrier or contractor enters into an agreement with the Secretary with respect to financial assistance under this subtitle;
Emphasis mine.